Ronald E. McNair Discovery Learning Academy media specialist Harold Grant welcomes children as they arrive at McNair High School. The learning academy held classes at McNair High School on Wednesday after a gunman on Tuesday held one or two staff members captive and fired into the floor of the school office. (ASSOCIATED PRESS / Atlanta Journal-Constitution, John Spink)

ATLANTA (AP) — President Barack Obama has praised as "remarkable" the actions of an Atlanta-area school bookkeeper who calmly persuaded a gunman to surrender during a frightening standoff and shooting this week.

Obama phoned bookkeeper Antoinette Tuff to commend her as she prepared for a television interview on Thursday, and then said in an interview that aired Friday that he was impressed with the way that she handled herself Tuesday.

"When I heard the 911 call and, you know, read the sequence of events, I thought, here's somebody who's not just courage and not just cool under pressure, but also had enough heart that somehow she could convince somebody that was really troubled that she cared about them," the president told CNN's Chris Cuomo. "And, you know, I told her, I said, that not only did she make Michelle and me proud, but she probably saved a lot of lives, including the life of the potential perpetrator."

Tuff had said she was thrilled to receive Obama's call and would like to meet him, and the president indicated that an invitation to the White House might be in the works.

"I think we might have to have her maybe make a visit to the White House," Obama said.

Obama's remarks came a few days after police say Tuff helped persuade Michael Brandon Hill, 20, to surrender following a standoff and shooting Tuesday at Ronald E. McNair Discovery Learning Academy in Decatur, a suburb east of Atlanta.

Police and school officials said that Tuff helped avert a tragedy with her quick thinking and calm and understanding demeanor after she was taken captive by Hill, who has a history of mental health issues. He went to the school armed with an AK 47-style rifle and nearly 500 rounds of ammunition, police said.

Lines of young students raced out of the building with police and teachers escorting them to safety, recalling the chaotic scene last December outside a Connecticut elementary school, where a gunman killed 20 students and six educators.

On a recording of a 911 call released Wednesday, Tuff can be heard relaying messages from Hill to DeKalb County emergency dispatcher Kendra McCray before convincing the gunman to give up. She tells the dispatcher that Hill said he wasn't there to hurt the children but wanted to talk to an unarmed officer.

"He said he should have just went to the mental hospital instead of doing this, because he's not on his medication," Tuff is heard telling the dispatcher.

No one was injured, but police said the suspect shot into the floor and exchanged gunfire with officers who had surrounded the school, which has 870 students in pre-kindergarten through fifth grade. Tuff urged him to come back inside and give up.

"I knew (police) were gonna kill him. And I knew he was not in his right state of mind," she told CNN's Anderson Cooper on Thursday night.

On the program, she also had a tearful on-air reunion with McCray, the dispatcher who stayed on the phone with her as she reassured Hill that surrendering peacefully was the right thing to do. She got the call from Obama in a makeup room before the taping, and said Obama wanted her to know how proud he was of her.

"You can't get any better when you have a great leader in front of you," a beaming Tuff is shown telling the president.

Time and again, Tuff has stressed that her faith got her through the episode.

"That was nobody but God's grace and mercy, because I can truly tell you I was terrified inside," she said.

She said she was praying the entire time she talked with Hill, asking God what she should say.

McCray said she was frightened, too, particularly when Tuff began telling her Hill was getting agitated.

"I had to put my phone on mute (and say), 'Hey, he's getting agitated. We have got to move.'"

Tuff is "a true hero," McCray said on the program. "You did so great. I've never had a caller where the caller was so calm and so confident in what they were saying and so personable. You made my job a whole lot easier."

Hill is charged with aggravated assault on a police officer, terroristic threats and possession of a firearm by a convicted felon, authorities said. Police declined to discuss what he told them when questioned.

The DeKalb County Public Defender's office said in a statement that it was representing Hill, calling him "a young man with a long history of mental health issues."

Police on Wednesday released an undated photo of Hill posing with an assault rifle that they believe is the one used at the school.

Authorities said Hill got the gun from an acquaintance, but it's not clear if he stole it or had permission to take it. His motive is still unclear.

The suspect's brother, Tim Hill, told CNN's Piers Morgan on Thursday that Michael Brandon Hill was a normal kid growing up, but began to change as a teenager and engage in behavior that was threatening to others.

"Once he started hitting his teenage years, something happened with him," Tim Hill said. "Everything just started changing after doctors started messing with his medicines here and there, and changing them up and putting him on a different one and institutionalizing him multiple times to correct his medicine. It just escalated from there."

He said Michael Hill set fire to the family's home when eight people were inside sleeping — the fire was discovered before it spread — and at another point their mother awoke to find him standing over her with a butcher's knife.

"My stepfather and mother ended up having to lock up...like all the knives in the trunk of the car, just to protect everybody in the home," Tim Hill told Morgan.

Tim Hill also confirmed that his brother threatened his life on Facebook, prompting him to call police.

"I honestly had no words for it, except fear. That's the only thing I can think of," he said.

Michael Hill was arrested in mid-March for making terroristic threats in Henry County, DeKalb and Henry County sheriff's officials have said. He was sentenced to probation.

Tim Hill expressed frustration that authorities hadn't done more to deal with his brother's mental condition before Tuesday. He said the president should focus more on the problems of troubled kids than just calling and congratulating Tuff, whose efforts he said he appreciates. Tim Hill said he doesn't believe his brother would have harmed Tuff or the schoolchildren.

"I don't think he was there to do that," Tim Hill said of his brother. "He's always had a problem with the cops."

But Tuff has said Michael Hill "had a look on him that he was willing to kill — matter of fact he said it. He said that he didn't have any reason to live and that he knew he was going to die today."

Tuff told CNN's Cooper she'd like to visit Hill and speak with him again.

"He's a hurting soul, and so if there's any kind of way I can help him and allow him to get on the right path — we all go through something," she said during the interview.